Gill Instruments Ltd
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WindObserver II (WindObserver FC)
Page 32
Issue 2
Doc. No. 1390-PS-0011
June 2007
10.3. Principle of operation
The WindObserver II (WindObserver FC) measures the times taken for an ultrasonic pulse
of sound to travel from the North transducer to the South transducer, and compares it with
the time for a pulse to travel from S to N transducer. Likewise times are compared
between West and East, and E and W transducer.
If, for example, a North wind is blowing, then the time taken for the pulse to travel from N
to S will be faster than from S to N, whereas the W to E, and E to W times will be the
same. The wind speed and direction (and the speed of sound) can then be calculated from
the differences in the times of flight on each axis. This calculation is independent of
factors such as temperature.
